The present invention relates to an agricultural and horticultural disease controller containing as an active ingredient a 1,2,3-thiadiazole derivative represented by the general formula (1), or a salt thereof: 
wherein R1 is {circle around (1)} a hydrogen atom, {circle around (2)} a (C1-C12)alkyl group, {circle around (3)} a halo(C1-C12)alkyl group, {circle around (4)} (C2-C12)alkenyl group, {circle around (5)} a halo(C2-C12)alkenyl group, {circle around (6)} a (C2-C12)alkynyl group, {circle around (7)} a halo(C2-C12)alkynyl group, {circle around (8)} a (C3-C6)cycloalkyl group, {circle around (9)} an unsubstituted phenyl group, {circle around (10)} a substituted phenyl group having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups, {circle around (11)} a group represented by the formula: 
(wherein R3 and R4, which may be the same or different, are hydrogen atoms, (C1-C12)alkyl groups or halo(C1-C12)alkyl groups, m is zero or an integer of 1 to 6, and R5 is a hydrogen atom; a (C1-C12)alkyl group; a halo(C1-C12)alkyl group; a (C2-C12)alkenyl group; a (C2-C12)alkynyl group; an unsubstituted phenyl group; a substituted phenyl group having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups; an unsubstituted phenyl(C1-C6)alkyl group; or a substituted phenyl(C1-C6)alkyl group having on the ring one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups), {circle around (12)} a group represented by the formula: 
(wherein R3, R4 and m are as defined above, and R6 and R7, which may be the same or different, are hydrogen atoms; (C1-C12)alkyl groups; halo(C1-C12)alkyl groups; (C2-C12)alkenyl groups; (C2-C12)alkynyl groups; (C1-C12)alkoxy(C1-C6)alkyl groups; (C1-C12)alkylthio(C1-C6)alkyl groups; cyano(C1-C12)alkyl groups; unsubstituted phenyl groups; substituted phenyl groups having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups; unsubstituted phenyl(C1-C6)alkyl groups; or substituted phenyl(C1-C6)alkyl groups having on the ring one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups; R6 and R7 being able to be taken together to represent a (C4-C6)alkylene group which may contain an oxygen atom between adjacent carbon atoms of the carbon chain), {circle around (13)} a group represented by the formula: 
(wherein R3, R4, R6 and R7, and n is an integer of 1 to 6), or {circle around (14)} a group represented by the formula: 
[wherein R3, R4 and n are as defined above, A is 
(wherein R9 is a hydrogen atom, a (C1-C12)alkyl group or a halo(C1-C12)alkyl group),
xe2x80x94Sxe2x80x94,
xe2x80x94Soxe2x80x94,
xe2x80x94SO2xe2x80x94, 
xe2x80x83{wherein R9 is as defined above, and R10 is a hydrogen atom, a (C1-C12)alkyl group or a halo(C1-C12)alkyl group, R9 and R10 being able to be taken together to represent a (C4-C6)alkylene group which may contain, between adjacent carbon atoms of the carbon chain, an oxygen atom, a sulfur atom or
Nxe2x80x94R11
xe2x80x83(wherein R11 is a hydrogen atom, a (C1-C12)alkyl group or a halo(C1-C12)alkyl group)}, or
xe2x80x94N(R10)
xe2x80x83(wherein R10 is as defined above), and R8 is a hydrogen atom; a (C1-C12)alkyl group; a halo(C1-C12)alkyl group; a (C2-C12)alkenyl group; a (C2-C12)alkynyl group; a (C1-C12)alkoxy(C1-C12)alkyl group; a (C1-C12)alkylthio(C1-C12)alkyl group; a cyano(C1-C12)alkyl group; an unsubstituted phenyl group; a substituted phenyl group having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups; an unsubstituted phenyl(C1-C6)alkyl group; a substituted phenyl(C1-C6)alkyl group having on the ring one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups; an unsubstituted 5- or 6-membered heterocyclic ring having one or more heteroatoms which may be the same or different and are selected from the group consisting of oxygen atom, sulfur atom and nitrogen atom; or a substituted 5- or 6-membered heterocyclic ring having one or more heteroatoms which may be the same or different and are selected from the group consisting of oxygen atom, sulfur atom and nitrogen atom, said substituted heterocyclic ring having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups], and R2 is (i) a group represented by the formula:
xe2x80x94Xxe2x80x94R12
xe2x80x83[wherein X is an oxygen atom or a sulfur atom, and R12 is {circle around (1)} a hydrogen atom, {circle around (2)} a (C1-C12)alkyl group, {circle around (3)} a halo(C1-C12)alkyl group, {circle around (4)} a (C2-C12)alkenyl group, {circle around (5)} a halo(C2-C12)alkenyl group, {circle around (6)} a (C2-C12)alkynyl group, {circle around (7)} a halo(C2-C12)alkynyl group, {circle around (8)} a hydroxy(C1-C6)alkyl group, {circle around (9)} a (C1-C12)alkoxy(C1-C12)alkyl group, {circle around (10)} a (C1-C12)alkylthio(C1-C12)alkyl group, {circle around (11)} a (C3-C6)cycloalkyl group, {circle around (12)} a (C3-C6)cycloalkyl(C1-C12)alkyl group, {circle around (13)} an unsubstituted phenyl group, {circle around (14)} a substituted phenyl group having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups, (C2-C6)alkynyl groups, and (C1-C6)alkoxycarbonyl (C1-C6)alkyloxy groups, {circle around (15)} an unsubstituted phenyl(C1-C6)alkyl group, {circle around (16)} a substituted phenyl(C1-C6)alkyl group having on the ring one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups, {circle around (17)} a diphenyl(C1-C6)alkyl group, {circle around (18)} a phenoxy(C1-C6)alkyl group, {circle around (19)} a group represented by the formula:
xe2x80x94Bxe2x80x94N(R13)R14
xe2x80x83{wherein B is a (C1-C6)alkylene group which may be substituted by a (C1-C6)alkyl group or a phenyl group, and R13 and R14, which may be the same or different, are hydrogen atoms; formyl groups; (C1-C12)alkyl groups; (C2-C12)alkenyl groups; (C2-C12)alkynyl groups; (C1-C6)alkylcarbonyl groups; unsubstituted phenyl groups; substituted phenyl groups having one or more substituents which may be the same or different and are selected from the group consisting of hydrogen atom, halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups; phenylcarbonyl groups; unsubstituted 1,2,3-thiadiazol-5-yl-carbonyl groups; or substituted 1,2,3-thiadiazol-5-yl-carbonyl groups having a halogen atom or a (C1-C6)alkyl group as the substituent; R13 and R14 being able to be taken together to represent a (C4-C5)alkylene group which may contain, between adjacent carbon atoms of the carbon chain, an oxygen atom, a sulfur atom or
Nxe2x80x94R11
xe2x80x83(wherein R11 is as defined above)}, {circle around (20)} a group represented by the formula:
xe2x80x94C(R15)xe2x95x90C(R16)xe2x80x94R17
xe2x80x83(wherein R15 is a hydrogen atom or a (C1-C6)alkyl group, R16 is a hydrogen atom, a halogen atom or a (C1-C6)alkyl group, and R17 is a nitro group, a cyano group, a (C1-C6)alkylcarbonyl group, a (C1-C6)alkoxycarbonyl group, a phenylcarbonyl group, or a substituted amino-carbonyl group having one or more substituents which may be the same or different and are selected from the group consisting of hydrogen atom, (C1-C12)alkyl groups, unsubstituted phenyl group, and substituted phenyl groups having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, cyano group, nitro group, (C1-C6)alkyl groups and (C1-C6)alkoxy groups, R15 and R17 being able to be taken together to represent a (C3-C6)alkylene group which may be substituted by one or more (C1-C6)alkyl group and/or an oxo group), {circle around (21)} a group represented by the formula: 
xe2x80x83(wherein two R18""s, which may be the same or different, are hydrogen atoms, (C1-C6)alkylcarbonyl groups, phenylcarbonyl groups, unsubstituted 1,2,3-thiadiazol-5-yl-carbonyl groups, or substituted 1,2,3-thiadiazol-5-yl-carbonyl groups having a halogen atom or a (C1-C6)-alkyl group as the substituent, and l is zero or an integer of 1 to 12), {circle around (22)} a 5- or 6-membered heterocyclic (C1-C6)alkyl group having one or more heteroatoms which may be the same or different and are selected from the group consisting of oxygen atom, sulfur atom and nitrogen atom, {circle around (23)} tri(C1-C6)alkylsilyl(C1-C6)alkyl groups, or {circle around (24)} 1,2,3-thiadiazol-5-yl-carbonyloxy-(C1-C12)alkyl groups having on the ring a halogen atom or (C1-C6)alkyl group as the substituent], (ii) a group represented by the formula:
xe2x80x94Oxe2x80x94Nxe2x95x90C(R19)R20
xe2x80x83[wherein R19 and R20, which may be the same or different, are {circle around (1)} hydrogen atoms, {circle around (2)} halogen atoms, {circle around (3)} nitro groups, {circle around (4)} cyano groups, {circle around (5)} (C1-C12)alkyl groups, {circle around (5)} halo(C1-C12)alkyl groups, {circle around (7)} (C3-C6)cycloalkyl groups, {circle around (8)} (C2-C12)alkenyl groups, {circle around (9)} (C2-C12)alkynyl groups, {circle around (10)} (C1-C12)alkoxy(C1-C12)alkyl groups, {circle around (11)} (C1-C12)alkoxycarbonyl groups, {circle around (12)} unsubstituted phenyl groups, {circle around (13)} substituted phenyl groups having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups, {circle around (14)} unsubstituted 5- or 6-membered heterocyclic rings having one or more heteroatoms which may be the same or different and are selected from the group consisting of oxygen atom, sulfur atom and nitrogen atom, {circle around (15)} substituted 5- or 6-membered hetero-cyclic rings having one or more heteroatoms which may be the same or different and are selected from the group consisting of oxygen atom, sulfur atom and nitrogen atom, said substituted heterocyclic ring having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups, {circle around (16)} groups represented by the formula;
xe2x80x94SR5
xe2x80x83(wherein R5 is as defined above), or {circle around (17)} groups represented by the formula:
xe2x80x94N(R6)R7
xe2x80x83(wherein R6 and R7 are as defined above), R19 and R20 being able to be taken together to represent {circle around (18)} a (C3-C6)cycloalkane ring or {circle around (19)} a 5- or 6-membered heterocyclic ring containing, between adjacent carbon atoms of the carbon chain, one or more hetero atoms which may be the same or different and are selected from the group consisting of oxygen atom, sulfur atom and nitrogen atom], (iii) a group represented by the formula:
xe2x80x94N(R21)R22
xe2x80x83[wherein R21 and R22, which may be the same or different, are {circle around (1)} hydrogen atoms, {circle around (2)} (C1-C12)alkyl groups, {circle around (3)} unsubstituted halo(C1-C12)alkyl groups, {circle around (4)} substituted halo(C1-C12)alkyl groups having a hydroxyl group or a (C1-C6)alkoxy group as the substituent, {circle around (5)} (C2-C12)alkenyl groups, {circle around (6)} (C2-C12)alkynyl groups, {circle around (7)} (C1-C12)alkoxy(C1-C6)alkyl groups, {circle around (8)} (C1-C12)alkylthio(C1-C6)alkyl groups, {circle around (9)} cyano(C1-C12)alkyl groups, {circle around (10)} substituted cyano(C1-C6)alkyl groups having on the alkyl chain a substituent selected from the group consisting of (C1-C6)alkoxy groups, (C2-C6)alkenyloxy groups, (C2-C6)alkynyloxy groups, (C1-C6)alkylthio groups, (C1-C6)alkoxycarbonyl(C1-C6)alkoxy groups, (C1-C6)alkoxycarbonyl(C1-C6)alkylthio groups, phenoxy group, phenylthio group and pyrazol-1-yl group, {circle around (11)} unsubstituted carbamoyl(C1-C6)alkyl groups, {circle around (12)} substituted carbamoyl(C1-C6)alkyl groups having on the alkyl chain a substituent selected from the group consisting of (C1-C6)alkoxy groups, (C2-C6)alkenyloxy groups, (C2-C6)alkynyloxy groups, (C1-C6)alkylthio groups, (C1-C6)alkoxycarbonyl(C1-C6)alkoxy groups, (C1-C6)alkoxycarbonyl(C1-C6)alkylthio groups, phenoxy group, phenylthio group and pyrazol-1-yl group, {circle around (13)} hydroxy-(C1-C6)alkyl groups, {circle around (14)} di(C1-C6)alkoxy(C1-C6)alkyl groups in which the (C1-C6)alkoxy groups may be the same or different, {circle around (15)} unsubstituted (C1-C6)alkoxycarbonyl-(C1-C6)alkyl groups, {circle around (16)} substituted (C1-C6)alkoxy-carbonyl(C1-C6)alkyl groups having on the alkyl chain a substituent selected from the group consisting of (C1-C6)alkyl groups, (C1-C6)alkoxy groups, (C2-C6)alkenyloxy groups, (C2-C6)alkynyloxy groups, (C1-C6)alkylthio groups, (C1-C6)alkoxycarbonyl(C1-C6)alkoxy groups, (C1-C6)alkoxycarbonyl(C1-C6)alkylthio groups, phenyl group, phenyl(C1-C6)alkyl group, phenoxy group, phenylthio group and pyrazol-1-yl group, {circle around (17)} unsubstituted phenyl groups, {circle around (18)} substituted phenyl groups having one or more substituents which may be the same or different and are selected from the group consisting of 1) halogen atoms, 2) nitro group, 3) cyano group, 4) (C1-C6)alkyl groups, 5) halo(C1-C6)alkyl groups, 6) (C1-C6)alkoxy groups, 7) halo(C1-C6)alkoxy groups, 8) (C1-C6)alkylthio groups, 9) halo(C1-C6)alkylthio groups, 10) (C2-C6)alkenyl groups, 11) (C2-C6)alkynyl groups, 12) (C1-C6)alkylcarbonyl groups, 13) carboxyl group, 14) (C1-C12)alkoxycarbonyl groups, 15) methylenedioxy group, 16) phenyl group, 17) groups represented by the formula: 
xe2x80x83(wherein R23 and R24, which may be the same or different, are hydrogen atoms; (C1-C12)alkyl groups; halo(C1-C12)alkyl groups; (C2-C12)alkenyl groups; (C2-C12)alkynyl groups; unsubstituted phenyl groups; substituted phenyl groups having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, cyano group, nitro group, (C1-C6)alkyl groups and (C1-C6)alkoxy groups; or 5- or 6-membered heterocyclic rings containing, between adjacent carbon atoms of the carbon chain, one or more hetero atoms which may be the same or different and are selected from the group consisting of oxygen atom, sulfur atom and nitrogen atom), 18) groups represented by the formula:
xe2x80x94SO2xe2x80x94R25
xe2x80x83(wherein R25 is a hydrogen atom, hydroxyl group, a (C1-C12)alkyl group, a halo(C1-C6)alkyl group, an unsubstituted phenyl group, a substituted phenyl group having as the substituent(s) one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, (C1-C6)alkyl groups and (C1-C6)alkoxy groups, unsubstituted 1,2,3-thiadiazol-5-yl group, or substituted 1,2,3-thiadiazol-5-yl groups having halogen atom, (C1-C6)alkyl group or (C1-C6)alkoxy group as the substituent), 19) groups represented by the formula: 
xe2x80x83(wherein R25 is as defined above), 20) groups represented by the formula: 
xe2x80x83(wherein R26 is a (C1-C6)alkyl group, a phenyl group or a phenyl(C1-C6)alkyl group), 21) groups represented by the formula:
xe2x80x94NHxe2x80x94SO2xe2x80x94R25
xe2x80x83(wherein R25 is as defined above), 22) groups represented by the formula: 
xe2x80x83(wherein R25 is as defined above), and 23) groups represented by the formula: 
xe2x80x83(wherein R26 is as defined above), {circle around (19)} unsubstituted phenyl(C1-C6)alkyl groups, {circle around (20)} substituted phenyl(C1-C6)alkyl groups having on the ring one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups, {circle around (21)} naphthyl groups, {circle around (22)} groups represented by the formula:
xe2x80x94(CH2)pNHR18
xe2x80x83(wherein R18 is as defined above, and p is an integer of 1 to 12), or {circle around (23)} 5- or 6-membered heterocyclic rings having one or more hetero atoms which may be the same or different and are selected from the group consisting of oxygen atom, sulfur atom and nitrogen atom, R21 and R22 being able to be taken together to represent {circle around (24)} a (C4-C6)alkylene group which may contain an oxygen atom between adjacent carbon atoms of the carbon chain, or {circle around (25)} a diaminomethylene group], (iv) a group represented by the formula:
xe2x80x94N(R6)NHR27
xe2x80x83[wherein R6 is as defined above, and R27 is {circle around (1)} a hydrogen atom, {circle around (2)} a (C1-C12)alkyl group, {circle around (3)} a halo(C1-C12)alkyl group, {circle around (4)} a (C2-C12)alkenyl group, {circle around (5)} a (C2-C12)alkynyl group, {circle around (6)} a (C1-C12)alkoxy(C1-C6)alkyl group, {circle around (7)} a (C1-C12)alkylthio(C1-C6)alkyl group, {circle around (8)} a cyano(C1-C12)alkyl group, {circle around (9)} an unsubstituted phenyl group, {circle around (10)} a substituted phenyl group having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups, {circle around (11)} an unsubstituted phenyl(C1-C6)alkyl group, {circle around (12)} a substituted phenyl(C1-C6)alkyl group having on the ring one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C1-C6)alkylthio groups, halo(C1-C6)alkylthio groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups, {circle around (13)} a group represented by the formula: 
xe2x80x83(wherein R6 is as defined above), {circle around (14)} a group represented by the formula: 
xe2x80x83(wherein R6 is as defined above), {circle around (15)} a group represented by the formula: 
xe2x80x83(wherein R6 and R7 are as defined above), or {circle around (16)} a group represented by the formula:
xe2x80x94SO2xe2x80x94R6
xe2x80x83(wherein R6 is as defined above)], (v) a group represented by the formula:
xe2x80x94NHN(R6)R27
xe2x80x83[wherein R6 and R27 are as defined above, R6 and R27 being able to be taken together to represent
xe2x80x83xe2x95x90C(R28)R29
xe2x80x83(wherein R28 and R29, which may be the same or different, are hydrogen atoms; (C1-C6)alkyl groups; halo(C1-C6)alkyl groups; (C3-C6)cycloalkyl groups; unsubstituted phenyl groups; substituted phenyl groups having one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, (C1-C6)alkyl groups and (C1-C6)alkoxy groups; or 5- or 6-membered heterocyclic rings containing, between adjacent carbon atoms of the carbon chain, one or more hetero atoms which may be the same or different and are selected from the group consisting of oxygen atom, sulfur atom and nitrogen atom; R28 and R29 being able to be taken together to represent a (C3-C6)cycloalkane ring or a 5- or 6-membered heterocyclic ring containing one or more sulfur atoms between adjacent carbon atoms of the carbon chain), or R6 and R27 being able to be taken together with the nitrogen atom to which they are bonded, to represent a 5- or 6-membered heterocyclic ring which may contain, between adjacent carbon atoms of the carbon chain, one or more hetero atoms which may be the same or different and are selected from the group consisting of oxygen atom, sulfur atom and nitrogen atom], or (vi) a group represented by the formula:
xe2x80x94N(R6)xe2x80x94OR30
xe2x80x83(wherein R6 is as defined above, and R30 is a hydrogen atom, a (C1-C12)alkyl group, a halo(C1-C12)alkyl group, a (C3-C6)cycloalkyl group, a (C1-C12)alkenyl group, a (C2-C12)alkynyl group, an unsubstituted phenyl(C1-C6)alkyl group, or a substituted phenyl(C1-C6)alkyl group having on the ring one or more substituents which may be the same or different and are selected from the group consisting of halogen atoms, nitro group, cyano group, (C1-C6)alkyl groups, halo(C1-C6)alkyl groups, (C1-C6)alkoxy groups, halo(C1-C6)alkoxy groups, (C2-C6)alkenyl groups and (C2-C6)alkynyl groups).
Japanese Patent Unexamined Publication No. 54-9272 discloses 1,2,3-thiadiazole-5-carboxylic acid derivatives, a process for production thereof and an agent containing the derivative and having herbicidal and growth-regulating effects.
The present inventors earnestly investigated for developing a novel agricultural and horticultural disease controller and consequently found that 1,2,3-thiadiazole derivatives or salts thereof, which include some of the compounds disclosed in U.S. Pat. No. 4,177,054, are useful for herbicide and growth segulater, whereby the present invention has been accomplished.
In the definition of the substituents of the 1,2,3-thiadiazole derivative of the general formula (I) used as the active ingredient of the agricultural and horticultural disease controller of the present invention, the halogen atom includes chlorine atom, bromine atom, iodine atom and fluorine atom. The term xe2x80x9c(C1-C12)alkyl groupxe2x80x9d means a linear or branched alkyl group of 1 to 12 carbon atoms, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl or the like. The term xe2x80x9chalo(C1-C12)alkyl groupxe2x80x9d means a substituted and linear or branched alkyl group of 1 to 12 carbon atoms having as the substituent(s) one or more halogen atoms which may be the same or different. The term xe2x80x9c(C2-C6)alkenyl groupxe2x80x9d means a linear or branched alkenyl group of 2 to 6 carbon atoms having a double bond. The term xe2x80x9chalo-(C2-C6)alkenyl groupxe2x80x9d means a substituted and linear or branched alkenyl group of 2 to 6 carbon atoms having as the substituent(s) one or more halogen atoms which may be the same or different. The term xe2x80x9c(C2-C6)alkynyl groupxe2x80x9d means a linear or branched alkynyl group of 2 to 6 carbon atoms having a triple bond. The term xe2x80x9chalo(C2-C6)alkynyl groupxe2x80x9d means a substituted and linear or branched alkynyl group of 2 to 6 carbon atoms having as the substituent(s) one or more halogen atoms which may be the same or different.
The term xe2x80x9c5- or 6-membered heterocyclic ring having one or more heteroatoms which may be the same or different and are selected from the group consisting of oxygen atom, sulfur atom and nitrogen atomxe2x80x9d means any heterocyclic ring derived from furan, thiophene, pyrrole, oxazole, thiazole, isothiazole, pyrazole, imidazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 1,2,4-triazole, pyridine, pyridazine, pyrimidine, pyrazine, pynolidine, piperidine, morpholine, thiamorpholine, dithiolane, dithian, piperazine, dioxelan, imidazolizine and the like.
Preferable examples of the substituents of the 1,2,3-thiadiazole derivative of the general formula (I) used in the present invention are as follows. There is preferably used a compound in which R1 is a (C1-C12)alkyl group, halo(C1-C12)alkyl group, (C3-C6)cycloalkyl group, (C2-C12)alkenyl group, halo(C2-C12)alkenyl group, (C2-C12)alkynyl group, halo(C2-C12)alkynyl group, unsubstituted phenyl group or substituted phenyl group, and R2 is xe2x80x94Xxe2x80x94R12. There is more preferably used a compound in which R1 is a (C1-C6)alkyl group such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl or n-hexyl, and R2 is a hydroxyl group, its salt, a thiol group, its salt, an amide group, or an anilide group.
There is most preferably used a compound in which R1 is a methyl group and R2 is a hydroxyl group, its salt, a thiol group, its salt, an amide group, or an anilide group.
As the salt of the 1,2,3-thiadiazole derivative of the general formula (I), there can be exemplified salts with alkali metals such as sodium, potassium, etc.; salts with alkaline earth metals such as calcium, magnesium, etc.; unsubstituted ammonium salt; substituted ammonium salts having one or more substituents which may be the same or different and are selected from the group consisting of (C1-C12)alkyl groups, unsubstituted phenyl group, substituted phenyl groups, unsubstituted benzyl group and substituted benzyl groups; and guanidium salt.
The 1,2,3-thiadiazole derivative of the general formula (I) or salt thereof used as the active ingredient of the agricultural and horticultural disease controller of the present invention can be produced, for example, by any of the processes exemplified below: 
wherein R1 is as defined above, R1 is a (C1-C6)alkyl group, Rxe2x80x3 is an amino group or a (C1-C6)alkyl group, and Hal is a halogen atom.
A compound of the general formula (XII) is reacted with a compound of the general formula (XI) to obtain a compound of the general formula (X). The compound (X) is cyclized after or without isolation to obtain a 1,2,3-thiadiazole derivative of the general formula (I-1). The derivative (I-1) is hydrolyzed after or without isolation to obtain a compound of the general formula (IX). The compound (IX) is halogenated after or without isolation, whereby the acid halide of the general formula (VIII) can be produced.
The compound of the general formula (XII) can be produced by the process described in J. Org. Chem., 43, 2087 (1978), Formation of Cxe2x80x94C bonds, Vol. 3, p. 259, 1979 (Georg Thime Publishers, Stuttgart), etc.
From the acid halide of the general formula (VIII) produced by the above process, the 1,2,3-thiadiazole derivative of the general formula (I) or salt thereof used as the active ingredient of the agricultural and horticultural disease controller of the present invention can be produced, for example, by any of the processes illustrated below.
Production Process 1 
wherein R1, R12, R21, R22 and Hal are as defined above.
The acid halide of the general formula (VIII) is reacted with an alcohol of the general formula (III) to obtain a 1,2,3-thiadiazole derivative of the general formula (I-2). The compound (I-2) is reacted with an amine of the general formula (II) after or without isolation of the compound (I-2), whereby a 1,2,3-thiadiazole derivative of the general formula (1I-3) can be produced.
The 1,2,3-thiadiazole derivative of the general formula (I-3) can be produced also by reacting the acid halide of the general formula (VIII) with an amine of the general formula (II).
Production Process 2 
wherein R19, R20 and Hal are as defined above.
A 1,2,3-thiadiazole derivative of the general formula (I-4) can be produced by reacting the acid halide of the general formula (VIII) with a compound of the general formula (IV).
Production Process 3 
wherein R6, R27 and Hal are as defined above.
A 1,2,3-thiadiazole derivative of the general formula (I-5) can be produced by reacting the acid halide of the general formula (VIII) with a compound of the general formula (V). Similarly, a 1,2,3-thiadiazole derivative of the general formula (I-6) can be produced by reacting the acid halide of the general formula (VIII) with a compound of the general formula (VI).
Production Process 4 
wherein R6, R30 and Hal are as defined above.
A 1,2,3-thiadiazole derivative of the general formula (I-7) can be produced by reacting the acid halide of the general formula (VIII) with a compound of the general formula (VII).
Typical compounds as the 1,2,3-thiadiazole derivative of the general formula (I) or a salt thereof are listed in Table 1 but they are not intended in any way to limit the scope of the present invention.
The abbreviations in the R1 column and R2 column in Table 1 stand for the following compounds:
Table 2 shows 1H-NMR data of the 1,2,3-thiadiazole derivatives having a physical property expressed by the word xe2x80x9coilxe2x80x9d, xe2x80x9cpastexe2x80x9d or xe2x80x9cNMRxe2x80x9d in Table 1.
The 1,2,3-thiadiazole derivatives of the general formula (I) or salts thereof according to the present invention are useful for agricultural and horticultural disease control. For example, the compounds listed in Table 1 are very effective in controlling various diseases, for instance, rice blast (Pyricularia oryzae), rice sheath blight (Rhizoctonia solani), rice helminthosporium leaf spot (Cochliobolus miyabeanus), powdery mildew of various host plants, such as powdery mildew of barley and wheat (Erysiphe graminis), oats crown rust (Puccinia coronata), rust of other plants, tomato late blight (Phytophthora infestans), late blight or Phytophthora rots of other plants, downy mildew of plants, such as cucumber downy mildew (Pseudoperonospora cubensis) and grape downy mildew (Plasmopara viticola), apple scab (Venturia inaequalis), apple alternaria leaf spot (Alternaria mali), pear black spot (Alternaria kikuchiana), citrus melanose (Diaporthe citri), cucumber bacterial blight (Pseudomonas syringae pv. lachrymans), tomato bacterial wilt (Pseudomonas solanacearum), cabbage black rot (Xanthomonas campestris), citrus canker (Xanthomonas citri (Hasse) Dowson), rice bacterial leaf blight (Xanthomonas oryzae), cabbage bacterial soft rot (Erwinia carotovora), and tobacco mosaic (Tobacco mosaic virus).
The agricultural and horticultural disease controller of the present invention is markedly effective in controlling the above-exemplified diseases which damage paddy field crops, upland crops, fruit trees, vegetables, other crops, flowers and ornamental plants, and the like. Therefore, the desired effects of the agricultural and horticultural disease controller of the present invention can be obtained by applying the disease controller to the paddy field water, stalks and leaves of fruit trees, vegetables, other crops, flowers and ornamental plants, soil, etc., at a season at which the diseases are expected to occur, before their occurrence or at the time when their occurrence is confirmed.
In general, the agricultural and horticultural disease controller of the present invention is used after being prepared into a conveniently usable form according to an ordinary manner for preparation of agrochemicals.
That is, the 1,2,3-thiadiazole derivative of the general formula (I) or salt thereof according to the present invention and, optionally, an adjuvant are blended with a suitable inert carrier in a proper proportion and prepared into a suitable preparation form such as a suspension, emulsifiable concentrate, soluble concentrate, wettable powder, granules, dust or tablets through dissolution, dispersion, suspension, mixing, impregnation, adsorption or sticking.
The inert carrier used in the present invention may be either solid or liquid. As the solid carrier, there can be exemplified soybean flour, cereal flour, wood flour, bark flour, saw dust, powdered tobacco stalks, powdered walnut shells, bran, powdered cellulose, extraction residue of vegetables, powdered synthetic polymers or resins, clays (e.g. kaolin, bentonite, and acid clay), talcs (e.g. talc and pyrophyllite), silica powders or flakes (e.g. diatomaceous earth, silica sand, mica and white carbon, i.e. synthetic, high-dispersion silicic acid, also called finely divided hydrated silica or hydrated silicic acid, some of commercially available products contain calcium silicate as the major component), activated carbon, powdered sulfur, powdered pumice, calcined diatomaceous earth, ground brick, fly ash, sand, calcium carbonate powder, calcium phosphate powder and other inorganic or mineral powders, chemical fertilizers (e.g. ammonium sulfate, ammonium phosphate, ammonium nitrate, urea and ammonium chloride), and compost. These carriers may be used alone or as a mixture thereof.
The liquid carrier is that which itself has solubility or which is without such solubility but is capable of dispersing an active ingredient with the aid of an adjuvant. The following are typical examples of the liquid carrier and can be used alone or as a mixture thereof. Water; alcohols such as methanol, ethanol, isopropanol, butanol and ethylene glycol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone and cyclohexanone; ethers such as ethyl ether, dioxane, Cellosolve, dipropyl ether and tetrahydrofuran; aliphatic hydrocarbons such as kerosene and mineral oils; aromatic hydrocarbons such as benzene, toluene, xylene, solvent naphtha and alkylnaphthalenes; halogenated hydrocarbons such as dichloroethane, chloroform, carbon tetrachloride and chlorobenzene; esters such as ethyl acetate, diisopropyl phthalate, dibutyl phthalate and dioctyl phthalate; amides such as di-methylformamide, diethylformamide and dimethylacetamide; nitriles such as acetonitrile; and dimethyl sulfoxide.
The following are typical examples of the adjuvant, which are used depending upon purposes and used alone or in combination in some cases, or need not to be used at all.
To emulsify, disperse, dissolve and/or wet an active ingredient, a surfactant is used. As the surfactant, there can be exemplified polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene higher fatty acid esters, polyoxyethylene resinates, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate, alkylarylsulfonates, naphthalenesulfonic acid condensation products, ligninsulfonates and higher alcohol sulfate esters.
Further, to stabilize the dispersion of an active ingredient, tackify it and/or bind it, there may be used adjuvants such as casein, gelatin, starch, methyl cellulose, carboxymethyl cellulose, gum arabic, polyvinyl alcohols, turpentine, bran oil, bentonite and ligninsulfonates.
To improve the flowability of a solid product, there may be used adjuvants such as waxes, stearates and alkyl phosphates.
Adjuvants such as naphthalenesulfonic acid condensation products and polycondensates of phosphates may be used as a peptizer for dispersible products.
Adjuvants such as silicon oils may also be used as a defoaming agent.
The content of the active ingredient may be varied as required. In dusts or granules, the suitable content thereof is from 0.01 to 50% by weight. In emulsifiable concentrates or flowable wettable powders, it is also from 0.01 to 50% by weight.
The present inventive agricultural and horticultural disease controller containing the 1,2,3-thiadiazole derivative of the general formula (I) or a salt thereof as an active ingredient is used to control various diseases in the following manner. That is, it is applied to a crop on which the diseases are expected to occur, or a site where the occurrence of the diseases is undesirable, as it is or after being properly diluted with or suspended in water or the like, in an amount effective for control of the diseases. For example, to control the diseases of paddy rice, said disease controller can be used by a method such as submerged application to a regular paddy field, application to a rice nursery bed, dressing of seeds for direct sowing on flooded paddy field, or seed disinfection.
The applying dosage of the present inventive agricultural and horticultural disease controller containing the 1,2,3-thiadiazole derivative of the general formula (I) or a salt thereof as an active ingredient is varied depending upon various factors such as a purpose, diseases to be controlled, a growth state of a plant, tendency of disease occurrence, weather, environmental conditions, a preparation form, an application method, an application site and application time. It may be properly chosen in the range of 0.1 g to 10 kg (in terms of the active ingredient) per 10 ares depending upon purposes.
The present inventive agricultural and horticultural disease controller containing the 1,2,3-thiadiazole derivative of the general formula (I) or a salt thereof as an active ingredient may be used in admixture with other agricultural and horticultural disease controllers in order to expand both spectrum of controllable diseases and the period of time when effective applications are possible or to reduce the dosage.
Typical examples and test examples of the present invention are described below but they should not be construed as limiting the scope of the invention.
In the examples, parts are all by weight.